feat: initial commit

internal/mailer/sendgrid.go

@@ -0,0 +1,67 @@
+package mailer
+
+import (
+	"bytes"
+	"fmt"
+	"text/template"
+	"time"
+
+	"github.com/sendgrid/sendgrid-go"
+	"github.com/sendgrid/sendgrid-go/helpers/mail"
+)
+
+type SendGridMailer struct {
+	fromEmail string
+	apiKey    string
+	client    *sendgrid.Client
+}
+
+func NewSendGrid(apiKey, fromEmail string) *SendGridMailer {
+	client := sendgrid.NewSendClient(apiKey)
+	return &SendGridMailer{
+		fromEmail: fromEmail,
+		apiKey:    apiKey,
+		client:    client,
+	}
+}
+
+func (s *SendGridMailer) Send(templateFile, username, email string, data any, isDevEnv bool) (int, error) {
+	from := mail.NewEmail(FromName, s.fromEmail)
+	to := mail.NewEmail(username, email)
+
+	tmpl, err := template.ParseFS(FS, "templates/"+templateFile)
+	if err != nil {
+		return -1, err
+	}
+
+	// Template Parsing and sending
+	subject := new(bytes.Buffer)
+	if err := tmpl.ExecuteTemplate(subject, "subject", data); err != nil {
+		return -1, err
+	}
+
+	body := new(bytes.Buffer)
+	if err := tmpl.ExecuteTemplate(body, "body", data); err != nil {
+		return -1, err
+	}
+
+	message := mail.NewSingleEmail(from, subject.String(), to, "", body.String())
+
+	message.SetMailSettings(&mail.MailSettings{
+		SandboxMode: &mail.Setting{
+			Enable: &isDevEnv,
+		},
+	})
+
+	var retryErr error
+	for i := 0; i < maxRetries; i++ {
+		resp, retryErr := s.client.Send(message)
+		if retryErr != nil {
+			//* Exponential backoff
+			time.Sleep(time.Duration(i+1) * time.Second)
+			continue
+		}
+		return resp.StatusCode, nil
+	}
+	return -1, fmt.Errorf("failed to send the email after %d attempts, error: %v", maxRetries, retryErr)
+}